连续钢桁梁逐跨架设支座分步安装施工技术

Construction Technology for Erection of Steel Truss Girders with the Bearing Installed in Step

蒙华(蒙西至华中)铁路公安长江公铁两用特大桥南岸滩地为4×94.5 m连续钢桁梁,采用首跨在支架上拼装,后续跨悬臂架设的施工方案。为解决钢桁梁架设过程中钢梁温度变化和挠度变形对临时支点的影响,以及墩顶起落梁大吨位千斤顶布置、多点同步控制难题,在首跨钢桁梁架设完成后立即起顶钢桁梁、卸落支架、精确调整钢桁梁三向位置、安装正式支座,然后悬臂架设后续钢梁并随架设进展分步安装支座,完成钢桁梁架设。所采用的施工技术有效解决了一联多跨连续钢桁梁总重较大,以及安装过程中温度应力、挠度变形和胀缩变形产生的水平位移问题。

The south bank beach of Gong’an Yangtze River rail-cum-road super large bridge of Mengxi-Huazhong railway is a 4×94.5 m continuous steel truss girder.The construction scheme of the first span assembled on the support and the subsequent span cantilever erection was adopted.In order to solve the influence of temperature change and deflection deformation of steel girder on the temporary fulcrum during erection of steel truss girder,as well as the difficult problems of large tonnage jack arrangement and multi-point synchronization control of pier top landing girder,after the erection of the first span steel truss is completed,the steel truss girder shall be lifted up and the support shall be removed immediately.Accurately adjust the three-direction position of the steel truss girder and install the formal bearing.Then cantilever erection of follow-up steel girder and installation of bearing step by step with the progress of erection to complete the erection of steel truss girder.In the type of multi-span continuous steel truss girder,the problems of large total weight,temperature stress,deflection deformation and horizontal displacement caused by expansion and contraction deformation during installation are effectively solved.